European patent EP-1-199549-A1 discloses a device using the Brillouin Scattering effect in an optical fiber for carrying out spectroscopic measurements and constitutes the most recent background with an invention field similar to the one disclosed in the present document.
The main innovative step included in the present invention is the use of the optical amplification by means of the Brillouin Scattering effect, combined with the spectral selectivity provided by the same Brillouin Scattering effect as a consequence of the narrowness of the Brillouin gain curve in an optical fiber.
To obtain the Brillouin amplification effect, the test and probe signals are introduced into the optical fiber in which the effect occurs on opposite ends and in opposite propagation directions, unlike the configuration disclosed in European Patent EP-1-199549-A1. This difference is associated with significantly different operation principles of the device which permit obtaining a high optical amplification level of the test signal together with the high Brillouin effect spectral selectivity.
The resolution in the optical spectral measurement with the device disclosed in the present invention is determined by the Brillouin gain curve spectral width, and it is not based on any passive filtering of the test signal by means of systems with diffraction gratings, Fabry-Perot interferometers or other similar systems.